The present invention relates to retrieval apparatus for retrieving a medical device from a patient's vessel. The preferred embodiment relates to a device for retrieving a filter in the vena cava.
Many types of implantable medical devices are intended to be employed in the vasculature of a patient for a limited period only, typically during the course of a medical treatment or while the patient is suffering from an ailment. Devices which are typically retrieved after a period of use include vena cava filters. These are deployed in the patient's vessel, left in position for a period during which filtration is deemed necessary and then removed from the patient. Effective designs of vena cava filters have a tulip or generally conical shape, which have been found to provide good filtration and a natural tendency for the wide end of the filter to open radially outwardly as a result both of the spring force generated by the filter structure and of the pressure from the blood stream. Such filters have proven to be very effective both in terms of filtration and in terms of reliably remaining in position in the vessel.
It is typical to deploy such filters via the femoral or jugular into the vena cava. On the other hand, as a result of their tulip or conical shape and the retrieval geometry, the withdrawal of such filters from the patient's vasculature is normally carried out from the jugular side. Such retrieval can involve the formation of a second percutaneous entry into the patient. It is not generally possible to remove such filters from the femoral side given the fact that the legs of the filter splay outwardly towards the vessel wall and usually have hooks or barbs to hold the filter in position.
There have been attempts to design filter assemblies which allow retraction of the filter from the deployment side. However, these normally involve a modified filter.
Examples of retrievable vascular filter assemblies can be found in US-2002/0045918, US-2005/0055046, US-2010/0030254, U.S. Pat. No. 5,531,788, US-2007/0198050 and US-2012/0078286.